The present invention relates to optoelectronic devices and, more particularly, to organic light emitting devices (organic EL devices). More specifically, the present invention relates to substantially stable organic EL devices, and which devices do not in embodiments, for example, degrade in the form of undergoing a rapid decrease in their efficiency at high temperatures, such as about 100xc2x0 C., and moreover, which devices are not substantially adversely affected by high temperatures.
An organic electroluminescent (EL) device can be comprised of a layer of an organic luminescent material interposed between an anode, typically comprised of a transparent conductor, such as indium tin oxide, and a cathode, typically a low work function metal such as magnesium, calcium, aluminum, or the alloys thereof with other metals. The EL device functions on the primary principle that under an electric field, positive charges (holes) and negative charges (electrons) are respectively injected from the anode and cathode into the luminescent layer and undergo recombination to form excitonic states which subsequently emit light. A number of organic EL devices have been prepared from a laminate of an organic luminescent material and electrodes of opposite polarity, which devices include a single crystal material, such as single crystal anthracene as the luminescent substance as described, for example, in U.S. Pat. No. 3,530,325, the disclosure of which is totally incorporated herein by reference. These types of devices are believed to require excitation voltages on the order of 100 volts or greater.
An organic EL device with a multilayer structure can be formed as a dual layer structure comprising one organic layer adjacent to the anode supporting hole transport, and another organic layer adjacent to the cathode supporting electron transport and acting as the organic luminescent zone of the device. Examples of these devices are disclosed in U.S. Pat. Nos. 4,356,429; 4,539,507; 4,720,432, and 4,769,292, the disclosures of which are totally incorporated herein by reference, wherein U.S. Pat. No. 4,769,292, the disclosure of which is totally incorporated herein by reference, discloses, for example, an organic EL device comprising three separate layers, a hole transport layer, a luminescent layer, and an electron transport layer, which layers are laminated in sequence and are sandwiched between an anode and a cathode, and wherein a fluorescent dopant material is added to the emission zone or layer whereby the recombination of charges results in the excitation of the fluorescent material. In some of these multilayer structures, such as, for example, organic light emitting devices described in U.S. Pat. No. 4,720,432, the disclosure of which is totally incorporated herein by reference, the organic light emitting device further comprises a buffer layer interposed between the hole transport layer and the anode. The combination of the hole transport layer and the buffer layer forms a dual-layer hole transport region, reference S. A. Van Slyke et al., xe2x80x9cOrganic Electroluminescent Devices with Improved Stability,xe2x80x9d Appl. Phys. Lett. 69, pp. 2160-2162, 1996, the disclosure of which is totally incorporated herein by reference.
There have also been attempts to obtain electroluminescence from organic light emitting devices containing mixed layers, for example, layers in which both the hole transport material and the emitting electron transport material are mixed together in one single layer, see, for example, Kido et al., xe2x80x9cOrganic Electroluminescent Devices Based On Molecularly Doped Polymers,xe2x80x9d Appl. Phys. Lett. 61, pp. 761-763, 1992; S. Naka et al., xe2x80x9cOrganic Electroluminescent Devices Using a Mixed Single Layer,xe2x80x9d Jpn. J. Appl. Phys. 33, pp. L1772-L1774, 1994; W. Wen et al., Appl. Phys. Lett. 71, 1302 (1997); and C. Wu et al., xe2x80x9cEfficient Organic Electroluminescent Devices Using Single-Layer Doped Polymer Thin Films with Bipolar Carrier Transport Abilitiesxe2x80x9d, IEEE Transactions on Electron Devices 44, pp. 1269-1281, 1997. In a number of these devices, the electron transport material and the emitting material can be the same or the mixed layer can further comprise an emitting material as a dopant. Other examples of organic light emitting devices which are formed of a single organic layer comprising a hole transport material and an electron transport material can be found, for example, in U.S. Pat. Nos. 5,853,905; 5,925,980; 6,114,055 and 6,130,001, the disclosures of which are totally incorporated herein by reference. As indicated in the article by S. Naka et al., these single mixed layer organic light emitting devices are generally less efficient than multilayer organic light emitting devices. These devices, which include only a single mixed layer of a hole transport material, such as NBP (N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine), and an emitting electron transport material, such as Alq3 (tris (8-hydroxyquinoline) aluminum), are believed to be unstable and to have poor efficiency. The instability of these devices is believed to be caused by the direct contact between the electron transport material in the mixed layer and the hole injecting contact comprised of indium tin oxide (ITO), which results in the formation of an unstable cationic electronic transport material, and the instability of the mixed layer/cathode interface, see H. Aziz et al., Science 283, 1900 (1999), the disclosure of which is totally incorporated herein by reference. In addition, the single mixed layer may result in high leakage currents and hence poor efficiency, see Z. D. Popovic et al., Proceedings of the SPIE, Vol. 3176, xe2x80x9cOrganic Light-Emitting Materials and Devices IIxe2x80x9d, San Diego, Calif., Jul. 21-23, 1998, pp. 68 to 73, the disclosure of which is totally incorporated herein by reference.
While recent progress in organic EL research has elevated the potential of organic EL devices for widespread applications, the operational stability of current available devices may in some instances be below expectations. A number of known organic light emitting devices have relatively short operational lifetimes before their luminance drops to some percentage of its initial value. Providing interface layers as described, for example, in S. A. Van Slyke et al., xe2x80x9cOrganic Electroluminescent Devices with Improved Stability,xe2x80x9d Appl. Phys. Lett. 69, pp. 2160-2162, 1996, and doping as described, for example, in Y. Hamada et al., xe2x80x9cInfluence of the Emission Site on the Running Durability of Organic Electroluminescent Devicesxe2x80x9d, Jpn. J. Appl. Phys. 34, pp. L824-L826, 1995, may perhaps increase the operational lifetime of organic light emitting devices for room temperature operation, however, the effectiveness of these organic light emitting devices deteriorates for high temperature device operation. In general, the device lifetime can be reduced by a factor of about two for each 10xc2x0 C. increment in the operational temperature. Moreover, at high temperatures, the susceptibility of the organic light emitting devices to degrade is increased as described, for example, in Zhou et al., xe2x80x9cReal-Time Observation of Temperature Rise and Thermal Breakdown Processes in Organic Leds Using an IR Imaging And Analysis Systemxe2x80x9d, Advanced Materials 12, pp 265-269, 2000, which further reduces the stability of the devices. As a result, the operational lifetime of these organic light emitting devices at a normal display luminance level of about 100 cd/m2 is limited, for example, to about a hundred hours or less at temperatures of about 60xc2x0 C. to about 80xc2x0 C., reference J. R. Sheats et al., xe2x80x9cOrganic Electroluminescent Devicesxe2x80x9d, Science 273, pp. 884-888, 1996, and also S. Tokito et al., xe2x80x9cHigh-Temperature Operation of an Electroluminescent Device Fabricated Using a Novel Triphenylamine Derivativexe2x80x9d, Appl. Phys. Lett. 69, 878 (1996).
Aspects of the present invention relate to an organic light emitting device comprising
(i) a first electrode;
(ii) a mixed region comprising a mixture of (1) a tertiary aromatic amine, (2) a metal oxinoid, and (3) a green emitting coumarin dye of the Formula 
xe2x80x83wherein X is selected from the group consisting of an oxygen atom, a sulfur atom, an alkyl imino group and aryl imino group; R1 and R2 are individually selected from the group consisting of alkyl, aryl, and carbocyclic; R3 and R4 are individually selected from the group consisting of a hydrogen atom, alkyl, and optionally a branched or unbranched 5 or 6 member substituent ring connecting with R1 and R2, respectively; and R5, R6, R7, and R8 are individually selected from the group consisting of a hydrogen atom, an alkoxy group and an alkyl group;
(iii) a second electrode;
(iv) an optional thermal protective element coated on one of the first and second electrodes, wherein one of the first and second electrodes is a hole injecting anode, and one of the first and second electrodes is an electron injecting cathode, and wherein the organic light emitting device further comprises at least one of
(v) a hole transport region interposed or situated between the anode and the mixed region, wherein the hole transport region optionally includes a buffer layer; and
(vi) an electron transport region interposed between the cathode and the mixed region, and wherein the green emitting dye is present in an amount of from about 0.01 to about 10 weight percent based on the total of the mixed layer components (ii); an organic light emitting device wherein the green emitting coumarin dye is 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T); an organic light emitting device wherein the tertiary aromatic amine is a N,N,Nxe2x80x2,Nxe2x80x2-tetraaryl benzidine; an organic light emitting device wherein the amine is an N,N,Nxe2x80x2,Nxe2x80x2-tetraaryl benzidine selected from the group consisting of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) and N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD), and the metal oxinoid is tris(8-hydroxyquinoline)aluminum (Alq3); an organic light emitting device wherein the hole transport region comprises at least one material selected from the group consisting of tertiary aromatic amines, porphyrins, and indolocarbazoles; and (ii) the electron transport region comprises at least one material selected from the group consisting of metal oxinoids, stilbenes, triazines, porphyrins, and quinolines; an organic light emitting device wherein the mixed region comprises from about 20 weight percent to about 80 weight percent of a tertiary aromatic amine; from about 80 weight percent to about 20 weight percent of the metal oxinoid; and from about 0.01 weight percent to about 10 weight percent of the coumarin dye, and wherein the weight percents are based on the total weight of materials comprising the mixed region; an organic light emitting device wherein the mixed region comprises from about 35 weight percent to about 65 weight percent of the tertiary aromatic amine; from about 65 weight percent to about 35 weight percent of the metal oxinoid; and from about 0.1 weight percent to about 4 weight percent of the coumarin dye, and wherein the weight percents are based on the total weight of materials comprising the mixed region; an organic light emitting device wherein the mixed region comprises from about 0.2 weight percent to about 2 weight percent of the coumarin dye, and wherein the weight percentages are based on the total weight of materials comprising the mixed region; an organic light emitting device wherein at least one of A. the material comprising the hole transport region and the tertiary aromatic amine comprising the mixed region are similar, and B. the material comprising the electron transport region and the metal oxinoid comprising the mixed region are similar; an organic light emitting device wherein at least one of A. the material comprising the hole transport region and the tertiary aromatic amine comprising the mixed region are different materials, and B. the material comprising the electron transport region and the metal oxinoid comprising the mixed region are different materials; an organic light emitting device wherein there is an electron transport region, and wherein the electron transport region comprises at least two layers; an organic light emitting device wherein (1) a first layer of the electron transport region is contacting the mixed region, and which first layer comprises a material selected from the group consisting of metal oxinoids and quinolines; and (2) a second layer of the electron transport region is contacting the cathode, and which second layer comprises a material selected from the group consisting of metal oxinoids, phthalocyanines, and triazines; an organic light emitting device wherein the first layer comprises a metal oxinoid comprising tris(8-hydroxyquinoline)aluminum (Alq3) or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), or a quinoline of 1,4-bis(4-phenylquinolin-2-yl)benzene, 4,4xe2x80x2-bis(4-phenylquinolin-2-yl)-1,1xe2x80x2-biphenyl (TA); and the second layer comprises a metal oxinoid of tris(8-hydroxyquinoline)aluminum (Alq3) or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq); a phthalocyanine of copper phthalocyanine (CuPc); or a triazine of 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, or 2,4,6-tris(4-biphenylyl)-1,3,5-triazine; an organic light emitting device wherein there is a hole transport region, and wherein the hole transport region comprises at least two layers; an organic light emitting device wherein (1) a first layer of the hole transport region is contacting the anode, and which first layer comprises a porphyrin; and (2) a second layer of the hole transport region is contacting the mixed region, and which second layer comprises a material selected from the group consisting of tertiary aromatic amines and indolocarbazoles; an organic light emitting device wherein the first layer comprises copper phthalocyanine; and the second layer comprises a tertiary aromatic amine of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD); or an indolocarbazole comprising 5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole, or 2,8-dimethyl-5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole; an organic light emitting device wherein there is present a hole transport region, and wherein the hole transport region comprises a layer comprised of a mixture of (i) from about 25 weight percent to about 99 weight percent of a porphyrin; and (ii) from about 75 weight percent to about 1 weight percent of an aromatic tertiary amine; an organic light emitting device wherein there is at least one of (1) an anode comprising a layer of indium-tin-oxide, and (2) a cathode comprising a layer selected from the group consisting of (i) Mg and Ag; (ii) Al; (iii) indium-tin-oxide; and (iv) an organic compound, Mg and Ag; an organic light emitting device wherein the cathode further comprises an alkaline metal or a compound thereof; an organic light emitting device wherein the alkaline metal is selected from the group consisting of Li, Na, K and Cs; an organic light emitting device wherein there is a thermal protective element, or layer present, and which thermal protective element comprises a layer of SiO, SiO2 or mixtures thereof; an organic light emitting device wherein the mixed region has a thickness of from about 5 nanometers to about 500 nanometers; the hole transport region has a thickness of from about 5 nanometers to about 250 nanometers; and/or the electron transport region has a thickness of from about 5 nanometers to about 100 nanometers; an organic light emitting device comprising
(i) an anode of indium-tin-oxide with thickness of from about 30 to about 300 nanometers coated on a substrate, the anode and the substrate being capable of transmitting at least about 70 percent of radiation of wavelength longer than about 400 nanometers;
(ii) a hole transport region on the anode comprised of at least one material selected from the group of materials including copper phthalocyanine (CuPc), N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB), N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD), 5,11-di-naphthyl-5,11-dihydroindolo [3,2-b]carbazole, and 2,8-dimethyl-5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole; and which region has a thickness of from about 5 nanometers to about 100 nanometers;
(iii) a mixed region situated on the hole transport region comprised of (1) from about 35 weight percent to about 65 weight percent of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD); (2) from about 65 weight percent to about 35 weight percent of tris(8-hydroxyquinoline) aluminum or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum; and (3) from about 0.2 weight percent to about 2 weight percent of 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T), wherein all weight percents are based on the total weight of materials comprising the mixed region, and wherein the thickness of the mixed region is from about 50 nanometers to about 150 nanometers;
(iv) an electron transport region situated on the mixed region comprised of tris(8-hydroxyquinoline)aluminum (Alq3) or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), wherein the thickness of the electron transport region is from about 5 nanometers to about 50 nanometers;
(v) a cathode situated on the electron transport region comprised of one of (1) a layer comprised of Mg:Ag alloy or Al of a thickness of from about 50 nanometers to about 500 nanometers; and (2) a first layer comprised of from about 40 volume percent to about 55 volume percent of Mg; from about 2 volume percent to about 10 volume percent of Ag and from about 55 volume percent to about 40 volume percent of Alq3, wherein the thickness of the first layer is from about 100 nanometers to about 600 nanometers, and coated with a second layer of thickness from about 50 nanometers to about 500 nanometers and comprising a metal or a metal alloy; and
(vi) a thermal protective element situated on the cathode comprised of SiO, SiO2 or mixtures thereof of a thickness of from about 100 nanometers to about 1,000 nanometers; an organic light emitting device comprising
(i) an anode of indium-tin-oxide with thickness of from about 30 to about 300 nanometers coated on a substrate, the anode and the substrate being capable of transmitting at least 70 percent of radiation of wavelength longer than 400 nanometers;
(ii) a hole transport region on or in contact with the anode comprised of at least one material selected from the group of materials including N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB), N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD), 5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole, and 2,8-dimethyl-5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole; and which region further comprises a buffer layer contacting the anode, and comprised of copper phthalocyanine wherein the thickness of the buffer layer is from about 10 nanometers to about 30 nanometers, and the thickness of the hole transport region is from about 5 nanometers to about 20 nanometers greater than the thickness of the buffer layer;
(iii) a mixed region situated on the hole transport region comprised of (1) from about 35 weight percent to about 65 weight percent of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD); (2) from about 65 weight percent to about 35 weight percent of tris(8-hydroxyquinoline) aluminum or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum; and (3) from about 0.2 weight percent to about 2 weight percent of 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T), wherein all weight percents are based on the total weight of materials comprising the mixed region, and wherein the thickness of the mixed region is from about 50 nanometers to about 150 nanometers;
(iv) an electron transport region situated on the mixed region comprised of tris(8-hydroxyquinoline)aluminum (Alq3) or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), wherein the thickness of the electron transport region is from about 5 nanometers to about 50 nanometers;
(v) a cathode situated on the electron transport region comprised of one of (1) a layer comprised of Mg:Ag alloy or Al of a thickness of from about 50 nanometers to about 500 nanometers; and (2) a first layer comprised of from about 40 volume percent to about 55 volume percent of Mg; from about 2 volume percent to about 10 volume percent of Ag and from about 55 volume percent to about 40 volume percent of Alq3, wherein the thickness of the first layer is from about 100 nanometers to about 600 nanometers; and coated with a second layer of a thickness from about 50 nanometers to about 500 nanometers comprising a metal or a metal alloy; and
(vi) an optional thermal protective element situated on the cathode comprised of SiO, SiO2 or mixtures thereof of a thickness of from about 100 nanometers to about 1,000 nanometers; an organic light emitting device and comprising
(i) an anode of indium-tin-oxide with a thickness of from about 30 to about 300 nanometers coated on a substrate, the anode and the substrate being capable of transmitting at least 70 percent of radiation of wavelength longer than 400 nanometers;
(ii) a hole transport region on the anode comprised of at least one material selected from the group of materials consisting of copper phthalocyanine (CuPc), N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB), N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD), 5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole, and 2,8-dimethyl-5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole; and which region has a thickness of from about 5 nanometers to about 100 nanometers;
(iii) a mixed region situated on the hole transport region comprised of (1) from about 35 weight percent to about 65 weight percent of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD); (2) from about 65 weight percent to about 35 weight percent of tris(8-hydroxyquinoline) aluminum or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum; and (3) from about 0.2 weight percent to about 2 weight percent of 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T), wherein all weight percents are based on the total weight of materials comprising the mixed region, and wherein the thickness of the mixed region is from about 50 nanometers to about 150 nanometers;
(iv) an electron transport region situated on the mixed region comprising (1) a first layer of a thickness of from about 5 nanometers to about 25 nanometers contacting the mixed region, wherein this first layer is comprised of tris(8-hydroxyquinoline)aluminum (Alq3), bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), or 1,4-bis(4-phenylquinolin-2-yl)benzene, 4,4xe2x80x2-bis(4-phenylquinolin-2-yl)-1,1xe2x80x2-biphenyl (TA); and (2) a second layer of a thickness of from about 5 nanometers to about 25 nanometers contacting the cathode, wherein the second is comprised of tris(8-hydroxyquinoline)aluminum (Alq3), bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), copper phthalocyanine (CuPc), 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, or 2,4,6-tris(4-biphenylyl)-1,3,5-triazine;
(v) a cathode situated on the electron transport region comprised of one of (1) a layer comprised of Mg:Ag alloy or Al of a thickness of from about 50 nanometers to about 500 nanometers; and (2) a first layer comprised of from about 40 volume percent to about 55 volume percent of Mg; from about 2 volume percent to about 10 volume percent of Ag and from about 55 volume percent to about 40 volume percent of Alq3, wherein the thickness of the first layer is from about 100 nanometers to about 600 nanometers; and coated with a second layer of a thickness of from about 50 nanometers to about 500 nanometers comprising a metal or a metal alloy; and
(vi) a thermal protective element situated on the cathode comprised of SiO, SiO2 or mixtures thereof of a thickness of from about 100 nanometers to about 1,000 nanometers; an organic light emitting device comprising
(i) an anode of indium-tin-oxide with a thickness of from about 30 to about 300 nanometers coated on a substrate, the anode and the substrate being capable of transmitting at least 70 percent of radiation of wavelength longer than 400 nanometers;
(ii) a hole transport region on the anode comprised of a material selected from the group of materials including N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB), N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD), 5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole, and 8-dimethyl-5,11-di-naphthyl-5,11-dihydroindolo[3,2-b]carbazole; and which region further comprises a buffer layer contacting the anode and comprised of copper phthalocyanine, wherein the thickness of the buffer layer is from about 10 nanometers to about 30 nanometers, and the thickness of the hole transport region is from about 5 nanometers to about 20 nanometers greater than the thickness of the buffer layer;
(iii) a mixed region situated on the hole transport region comprised of (1) from about 35 weight percent to about 65 weight percent of N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD); (2) from about 65 weight percent to about 35 weight percent of tris(8-hydroxyquinoline) aluminum or bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum; and (3) from about 0.2 weight percent to about 2 weight percent of 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T), wherein all weight percents are based on the total weight of materials comprising the mixed region, and wherein the thickness of the mixed region is from about 50 nanometers to about 150 nanometers;
(iv) an electron transport region situated on the mixed region comprising (1) a first layer of a thickness of from about 5 nanometers to about 25 nanometers contacting the mixed region, wherein this first layer is comprised of tris(8-hydroxyquinoline)aluminum (Alq3), bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), 1,4-bis(4-phenylquinolin-2-yl)benzene, or 4,4-bis(4-phenylquinolin-2-yl)-1,1xe2x80x2-biphenyl (TA); and (2) a second layer of a thickness of from about 5 nanometers to about 25 nanometers contacting the cathode, wherein the second is comprised of tris(8-hydroxyquinoline)aluminum (Alq3), bis(8-hydroxyquinolato)-(4-phenylphenolato)aluminum (Balq), copper phthalocyanine (CuPc), 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, or 2,4,6-tris(4-biphenylyl)-1,3,5-triazine;
(v) a cathode situated on the electron transport region comprised of one of (1) a layer comprising of Mg:Ag alloy or Al of a thickness of from about 50 nanometers to about 500 nanometers; and (2) a first layer comprised of from about 40 volume percent to about 55 volume percent of Mg; from about 2 volume percent to about 10 volume percent of Ag and from about 55 volume percent to about 40 volume percent of Alq3, wherein the thickness of the first layer is from about 100 nanometers to about 600 nanometers, and coated with a second layer of a thickness of from about 50 nanometers to about 500 nanometers comprising a metal or a metal alloy; and
(vi) an optional thermal protective element situated on the cathode comprised of SiO, SiO2 or mixtures thereof of a thickness of from about 100 nanometers to about 1,000 nanometers; an organic light emitting device wherein X is oxygen or sulfur; an organic light emitting device wherein X is an alkyl amino group wherein alkyl contains from about 1 to about 20 carbon atoms; an organic light emitting device wherein X is an aryl imino group wherein aryl contains from about 6 to about 36 carbon atoms; an organic light emitting device wherein R1 and R2 alkyl contain from about 1 to about 20 carbon atoms, and R1 and R2 aryl contain from about 6 to about 36 carbon atoms; an organic light emitting device wherein R3 and R4 alkyl contain from about 1 to about 20 carbon atoms; an organic light emitting device wherein R5, R6, R7 and R8 alkoxy contain from about 1 to about 20 carbon atoms, and alkyl contains from about 1 to about 20 carbon atoms; an organic light emitting device wherein the protective layer is comprised of a silicon dioxide or a silicon oxide; an organic light emitting device wherein the hole transport region is present; the electron transport region is present; or the hole transport region and the electron transport region are present; an organic light emitting device wherein the regions comprise from about 1 to about 20 layers; an organic light emitting device wherein the regions comprise from about 1 to about 5 layers; an organic light emitting device wherein the regions are each from about 1 to about 3 layers; an organic light emitting device wherein the regions are each from about 2 to about 4 layers; an organic light emitting device wherein the regions are each one layer; an organic light emitting device wherein the emitter amount is from about 0.01 to about 5 weight percent; an organic light emitting device wherein the enitter amount is from about 0.2 to about 2 weight percent; a device comprising
(i) a first electrode;
(ii) a mixed region comprising a mixture of (1) a tertiary aromatic amine, (2) a metal oxinoid, and (3) a green emitting coumarin dye of the Formula 
xe2x80x83wherein X is selected from the group consisting of an oxygen atom, a sulfur atom, an alkyl imino group and an aryl imino group; R1 and R2 are individually selected from the group consisting of alkyl, aryl, and carbocyclic; R3 and R4 are individually selected from the group consisting of a hydrogen atom, alkyl, and optionally a branched or unbranched 5 or 6 member substituent ring connecting with R1 and R2, respectively; and R5, R6, R7, and R8 are individually selected from the group consisting of a hydrogen atom, an alkoxy group and an alkyl group;
(iii) a second electrode;
(iv) an optional thermal protective element coated on one of the first and second electrodes, wherein one of the first and second electrodes is a hole injecting anode, and one of the first and second electrodes is an electron injecting cathode, and wherein the organic light emitting device further comprises at least one of
(v) a hole transport region interposed or situated between the anode and the mixed region, wherein the hole transport region optionally includes a buffer layer; and
(vi) an electron transport region interposed between the cathode and the mixed region, and wherein the green emitting dye is present in an amount of from about 0.01 to about 10 weight percent based on the total of the mixed layer components (ii); and which devices possess in embodiments thereof (i) excellent, such as high stability, such as a half-life exceeding about 5,000 hours from an initial luminance of 100 cd/m2 even when operated at a high temperature of about 70xc2x0 C. to about 100xc2x0 C.; (ii) an increased electroluminescence efficiency, amounting to, for example, in embodiments, at least 8.4 cd/A; (iii) an improved green color purity, such as, for example, color coordinates of 0.304, 0.617 on the C.I.E. chart; and/or full color display devices; an electroluminescent device (EL) comprised of
(i) a first electrode like an anode;
(ii) a mixed region comprising a mixture of (1) a tertiary aromatic amine, (2) a metal oxinoid, and (3) a red emitting material as illustrated in copending application U.S. Ser. No. 10/005,404, the disclosure of which is totally incorporated herein by reference, or a green emitting coumarin dye encompassed by Formula I 
xe2x80x83wherein X is selected from the group consisting of an oxygen atom, a sulfur atom, an alkyl imino group like R9xe2x80x94Nxe2x95x90, wherein R9 is an alkyl group with, for example, from about 1 to about 10 carbons, and an aryl imino group like Arxe2x80x94Nxe2x95x90, wherein Ar is aryl like a phenyl group; R1 and R2 are individually selected from the group consisting of alkyl of, for example, from 1 to about 20 carbon atoms, aryl, and carbocyclic systems; R3 and R4 are individually selected from the group consisting of a hydrogen atom, alkyl of from 1 to 10 carbon atoms, and a branched or unbranched 5 or 6 member substituent ring connecting with R1, R2, respectively; and R5, R6, R7, and R8 are individually selected from the group consisting of a hydrogen atom; an alkoxy group of, for example, from 1 to about 10 carbon atoms; and an alkyl group of, for example, from 1 to about 20 carbon atoms; a second electrode, reference for example U.S. Pat. No. 6,020,078, the disclosure of which is totally incorporated herein by reference,
(iii) an optional thermal protective element coated on at least one of the first and second electrodes, wherein one of the first and second electrodes is a hole injection anode, and one of the electrodes is an electron injection cathode, and wherein the organic light emitting device further comprises at least one of
(iv) a hole transport region situated between the anode and the mixed region, wherein the hole transport region optionally includes a buffer layer; and
(v) an electron transport region situated between the cathode and the mixed region, wherein region throughout refers, for example, to at least one layer, and more specifically, from 1 to about 10 layers, from 2 to about 7 layers, from 2 to about 3 layers, and the like, each layer with a thickness of, for example, from about 5 to about 5,000 nanometers.
A specific example of a green emitting compound is the coumarin dye 10-2-(benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)benzopyropyrano (6,7,-8-ij) quinolizin-11-one (C545T; and wherein the tertiary aromatic amine is N,Nxe2x80x2-di(naphthalene-1-yl)-N,Nxe2x80x2-diphenyl-benzidine (NPB) or N,Nxe2x80x2-bis(p-biphenyl)-N,Nxe2x80x2-diphenyl benzidine (biphenyl TPD) and the metal oxinoid is tris(8-hydroxyquinoline) aluminum (AlQ3).